Gasoline anti-stalling composition



United States Patent 3,336,123 GASOLINE ANTI-STALLIN G COMPOSITIONHoward Dudley Clile Hill, Wilmington, Del., assignor to E. I. du Pont deNemours and Company, Wilmington, DeL, a corporation of Delaware NoDrawing. Filed June 24, 1964, Ser. No. 377,527 6 Claims. (Cl. 44-56) Thepresent invention is directed to an improved gasoline compositioncontaining an additive which not only prevents stalling due tocarburetor icing but also reduces deposition of objectionable gums andcarbonaceous materials in the carburetors of internal combustionengines.

A common occurrence in the operation of an internal combustion engine isfrequent engine stalling in climates Where high humidity is common withtemperatures between about 30" F. and 60 F. This stalling is attributedto the formation of ice particles in the carburetor, especially on thethrottle plate and surrounding body walls. The formation of ice in thecareburetor, known as carburetor icing, is caused by a temperaturereduction in the metal parts of the carburetor as the fuel vaporizes.This lower temperature in turn causes the moisture in the air cominginto the carburetor to condense and freeze at the edge of the throttleplate and on the air bleeds of the carburetor. Ice formation at the edgeof the throttle plate reduces the flow of air to the engine therebycausing the engine to stall. On the other hand, ice formation on the airbleeds or venturi causes the engine to stall from excessively richmixtures of gasoline.

Ice formation also occurs in the emulsion tube type carburetor which isused extensively in foreign-make cars. This type of carburetor comprisesan emulsion tube in which the air and gasoline are mixed, metered andthen carbureted. Ice initially forms at the air correction inlet of theemulsion tube and eventually causes the engine to stall.

Frequent engine stalling also results from operating conditions atidling speeds in heavy stop-and-go trafiic. The reason for the engine tostall in such traffic is due mainly to an accumulation of deposits onthe walls of the carburetor throttle body which is below the closedportion of the throttle plate. Deposits of such foreign materials areable to enter the carburetor during periods of engine idling because theair filter at idling speeds is relatively inelfective. Most contaminantswhich enter the carburetor are those thrown out of the engine throughthe crankcase blowby. These contaminants remain trapped under the hoodWhile the engine is idling and the car is stopped. Other sources ofcontaminants are exhaust fumes from the carahead and the normal smokeand dust which accumulate in the air as a result of heavy trafficconditions. A common remedy used to eliminate this problem is theadjustment of the engine to higher idling speeds. Thisaction, however,is uneconomical since it wastes gasoline.

The problem of carburetor icing has become more pronounced in recentyears due to a trend in the use of more volatile gasolines which providegood cold-starting and warm-up characteristics. The tendency forcarburetor icing has been closely correlated to the degree of volatilityof the gasoline. The gasolines most affected by carburetor icing andtherefore the gasolines to which this invention is directed arecharacterized by having a mid-boiling point of less than about 245 F. asdetermined by A.S.T.M. distillation method.

It is, therefore, an object of the present invention to provide animproved gasoline for internal combustion engines which reduces enginestalling not only by pre venting ice formation in the carburetor butalso by reducing depositions of objectionable gum and other carbonaceousmaterials in the carburetor.

More specifically, the present invention is directed to a gasolinecomposition containing as an anti-stalling agent and effective amount ofa salt of (a) linoleic acid dimer or trimer and (b) a dialkylaminopropylcarboxamide of the formula AcNHCH CH CH -NRR', wherein Ac is a C to Cfatty or naphthenyl acyl group and R and R are the same or differentalkyl groups of 1 to 4 carbon atoms.

The linoleic acid dimer and trimer salts of the N-(3-dialkylaminopropyl) fatty and naphthenic acid amides utilized in thepresent invention may be prepared according to any of the methods of theart. For instance, the salts can be formed by neutralizing the acid withthe amine. This is accomplished by thoroughly mixing the two componentsat slightly elevated temperatures in the range of from 30 C. to 50 C.The salt may be prepared in a solvent such as methanol, toluene, xyleneor kerosene in sufiicient quantity to make a 50 to percent by weightsolution of the salt. The preferred solvent is methanol. Such aconcentrate is a convenient means for handling the salt and facilitatesthe blending of the salt composition into the base gasoline. The saltsof the present invention which are especially effective as anti-stallingagents and therefore preferred are the linoleic acid dimer salt ofN-(B-dimethylaminopropyl) oleamide, the linoleic acid dimer salt ofN-(3-dimethylaminopropyl) tallamide, and the linoleic acid trimer saltof N-(3-dimethylaminopropyl) tallamide.

Neither the amine nor acid components of the salts utilized in thepresent invention are alone effective as anti-icing or detergent agentin gasoline. Thus, since the salt is the active ingredient in thegasoline composition, the effectiveness of the gasoline to preventstalling is directly dependent on the concentration of the neutral saltin the gasoline. However, excess amounts of the amine or acid with thesalt are not detrimental to the performance of the salt and usually, dueto the method of preparation, these materials are present with the saltadditive. In general, a sufiicient amount of the amine component isemployed to neutralize from 1 to 2 carboxylic acid groups of the dimeracid and from 1 to 3 carboxylic acid groups of the trimer acid. Usuallyat least one half and preferably all of the carboxylic acid groups areneutralized, i.e., one amine equivalent is used for each carboxylic acidequivalent to make the neutral salt. Excess of the amino amide may beemployed, but, as hereinbefore stated, is unnecessary and tends to bewasteful.

The amount of salt added to the gasoline is not critical as long as itis suflicient to improve the antistalling characteristics of thegasoline. The preferred amount of the salt added to the gasoline is fromabout 0.001% to about 0.02% by Weight based on the weight of thegasoline.

The fatty acid amino amides are conveniently obtained as described inUS. Patent 2,805,925 by condensing one mole of the di-C -C-alkylaminopropylamide with one mole of a C C aliphatic orcycloaliphatic carboxylic acid, such as pelargonic, oleic, stearic andnaphthenic acids, tall oil (a mixture of oleic, linoleic, and rosinacids) and coconut oil fatty acids which consist principally of analiphatic acid containing 12 carbon atoms together with lesser amountsof other straight-chain acids containing an even number of from 8 to 18carbon atoms. The naphthenic acids utilized to form the amides in thepresent invention are normally obtained from petroleum and may bedefined chemically as monobasic carobxylic acids, RCOOH, where R is anaphthenic radical. The naphthenic radicals are predominantly derivedfrom cyclopentane, homologs of cyclopentane and their bicyclicderivatives, and to a lesser degree from cyclohexane. The carboxyl groupis usually linked to a paraffiuic side-chain but may be attacheddirectly to a ring carbon atom. The ring,

which may be monoand bicyclic, may have alkyl substituents. Typicalcommercial naphthenic acids are mixtures of cycloaliphatic acidscontaining from about 8 to 18 carbon atoms and boiling between about 200C. and 300 C. at atmospheric pressure, or between about 160 C. and 200C. at 6 mm. of mercury pressure. A suitable typical mixture ofnaphthenic acids has an average acid number of approximately 247,corresponding to an average molecular weight of about 227 (about 13carbon atoms in the molecule). Representative examples of naphthenicacids are 3-cyclopentylpropionic, 4-cyclohexylbutyric,l-methylcyclohexane carboxylic, 3,3,4-trimethylcyclopentylacetic, anddecalin-Z-carboxylic acid. Technical grades of the acids may be used inthe condensation. The condensation normally is effected between 120 C.and 200 C. and one mole equivalent of water is evolved. Use of ahydrocarbon solvent facilities the removal of the water by azeotropicdistillation. Such solvent, as desired, can be either left in theproduct or separated from it by distillation.

The linoleic acid dimer and linoleic acid trimer utilized in thisinvention are commercially available materials. The preparation of sucha dimer and trimer is described in US. Patent 2,482,761 and in anarticle by Charles G. Goebel, Journal of the American Oil ChemistsSociety, vol. 24, pp. 65-8 (1947). Since commercial linoleic acid maycontain small amounts of other fatty acids, dimers or trimers of theseacids may also be present in the product used in this invention. It isalso well known in the art that the linoleic dimer acids may containfrom small to substantial amounts of linoleic trimer acid and also minoramounts of unreacted acid. Likewise, the commercial linoleic trimer acidmay contain from small to substantial amounts of linoleic dimer acid andalso minor amounts of unreacted acids. Commercial linoleic acid dimersor timers which are substantially all dimer acid or trimer acid, ormixtures of the two, are suitable for use in the invention.

Naturally, the gasoline compositions of this invention may contain allthe additives incorporated in modern gasoline in addition to the subjectanti-stalling additive. Such additives as anti-knock agents,anti-oxidants, dyes, and metal deactivators do not affect theperformance of the salts of this invention and are compatible ingasolines with the subject anti-stalling agents.

For a clearer understanding of the present invention, the followingspecific examples are given. These examples are intended to beillustrative of the present invention and not in limitation thereof inany respect. All parts are by weight unless otherwise specified.

EXAMPLE I Gasoline samples containing the neutral salts of thisinvention were prepared for testing in an internal combustion engine.The tests were made to determine the effect of the additives of thepresent invention in improving the characteristics of gasolines inrespect to their abilities to prevent carburetor icing and carburetordeposits. The samples were prepared by adding to the gasoline smallamounts of technical grades of linoleic acid dimer or linoleic acidtrimer salts of aliphatic acid amides of N-(3-dimethylarninopropyl)amine and/or N-(3-di-n-butylaminopropyl) amine, as more fully describedin Tables I, II, and III below.

The gasoline used in the tests was commercial available and had thefollowing inspection data:

Reid vapor pressure p.s.i. 13.0 A.S.T.M. distillation (D86), F.:

End point 406 The following is a brief discussion of the test proceduresand equipment used to evaluate these samples.

Anti-icing test Type of Carburetor Throttle Plate Emulsion Tube Intakeair, F 38-40 34-60. Relative humidity, percent- 98-100..- 98-100. Engineload, horsepower 10 15. Engine speed, r.p.m... 1,500 33 high 1,500initially.

spee Idle speed, r.p.m 350 FigeIIE Temperatui'e to carburetor,

(a) Throttle plate carburetor The operating time of the engine wasvaried at the conditions described above, using the time required forstalling as a measure of the fuels tendency to cause or prevent stallingdue to carburetor icing. All runs were started after soaking thethrottle plate with methanol for 0.5 minute at a temperature of 40 F.The operating time selected for the engine depended on the ice-formingtendencies of the fuel. Operating times at the 1500 r.p.m. engine speedwere usually in the 0.5-1.5 minute range for uninhibited base fuels. Atthe end of the 1500 r.p.m. portion of the operating cycle, the throttlewas cut back to idle position. If no stall occurred within 30 seconds atidle, the run was repeated for a longer period at 1500 r.p.m. until atime was found when the engine stalled within 30 seconds afterconverting back to idle. The anti-stall rating or stall time of agasoline was defined as the longest 1500 r.p.m. run (to the nearest 0.25minute) followed by a complete 30-second idle period without stalling. Astall time of 3 or more minutes was considered excellent performance.

(b) Emulsion tube carburetor A Solex, Model No. 32 PBICA, single barrel,down draft carburetor adapted to 12" extension of 1 /2" pipe on intakemanifold, was substiuted for the throttle plate carburetor and theengine was operated under the conditions as listed. Under theseconditions, using the Solex emulsion type carburetor, the engine doesnot stall completely. The engine is operated for 20 minutes on the testfuel at an initial speed of 1500 r.p.m., and the reduction in enginespeed is taken as a measure of the effectiveness of the anti-icingagent. A winter grade base fuel may result in a loss in speed of over600 r.p.m. during the 20-minute period. A reduction of not more than 50r.p.m. on operating for 20 minutes is considered excellent antiicingperformance.

For the purposes of demonstrating the eifectivness of the subjectadditives, runs were made on gasolines both with and without additive.The results of the tests are set forth in the following tables. Table Icontains the results obtained while operating the engine with thethrottle plate carburetor and Table II contains the results obtainedwith the Solex carburetor or emulsion tube type carburetor. Table IIIshows that the /2 neutral, /3 neutral and neutralN-(3-dimethylaminopropyl) oleamide salts of linoleic acid dimer areeffective anti-icing agents in the emulsion tube carburetor and alsothat the effectiveness of the salt is not diminished by the presence ingasoline of additional quantities of the linoleic acid dimer and trimeror amine amide. Table III also shows the effect of the concentration ofthe neutral salt on the anti-icing characteristics of the gasolinecomposition in the emulsion tube type carburetor engine. 5

TABLE 1 Effect of Additive on Engine Stalling Due to Carburetor IcingUsing the Throttle Plate Carburetor Test Additive Engine Additive 1Cone., Wt. Stall Percent Time, Minutes Base Gasoline, Control None 0.25

Linoleic Acid dimer salt of N -(3-di u.1ethyl- 0.0067 1.

aminopropyl) tallamide 0. 0093 2. 00 0.0150 3.00

Linoleic Acid dimer salt of N -(3-dimethy1- 0. 0040 1.00 aminopropyl)oleamide 0.0150 3. 00

A 1 In each instance the indicated salt involved sufiicient amine toneu- 2O tralize all the carboxylic acid groups of the acid component.

TABLE IL-EFFECT OF ADDITIVE ON CARBURETOR ICING USING THE EMULSION TUBETYPE CARB U- RETOR TEST 25 Engine r.p.m.

Additive Loss During Additive 1 C0nc., Wt. 20 Minutes Percent Operationunder Test Conditions Base Gasoline, Control None 600N-(3-dimetliylaminopropyl) stearamide 0. 004 600N-(3-dimethylaminopropyl) tallamide- 0.004 600 N-(3-dibutylaminopropyl)oleamide.-

Linolcie acid dlmer 0 (no 175 Linoleic acid trimer 0. 004 150 Linoleicacid dimer salt of N- (ddimethylaminopropyl) stearamide 0. 004 0Linoleic acid dimer salt of N -(3-dirnethylaminopropyl) naphthamide 0.004 0 Linoleic acid dimer salt of N-(3- dimethylamiuoproply) tallamide0. 004 50 Linoleic acid dimer salt of N-(3-di- 4O methylaminopropyl)pelargonamide- 0. 0053 50 Linoleic acid dimer salt of N-(3-dimethylaminopropyl) oleamide 0. 004 10 Linoleic acid dimer salt of N-(3- dibutylaminopropyl) oleamide 0.010 50 Linoleic acid trimer salt ofN-(3- dimethylaminopropyl) tallamide 0. 004 25 Linoleic acid trimer saltneutral) of N-(3-dimethylaminopropyl) tallam1de o. 004 25 1 In each saltinstance, except where indicated, the salt involved sufficient amine toneutralize all the carboxylie acid groups of the acid component.

TABLE n1.nrrncr or ADDI'IIVE NEUTRALITY AND CONCENTRATION ON ANTI-ICINGUSING THE EMUL- SION TUBE TYPE CARBURETOR TEST Engine r.p.m. Loss During20 Additives and Concentration Minutes Operation under Test ConditionsBase Gasoline, Control (No additive) 600 0.0005 wt. Linoleio acid dimersalt (neutral) of N-(3- dimethylaminopropyl) oleamide plus 0.002 wt. N-6 (B-dimethylaminopropyl) oleamide 225 0 0.0018 wt. Linoleic acid dimersalt (neutral) of N-(S- dimethylaminopropyl) oleamide plus 0.0032 wt. N(3-dimethylaminopropyl) oleamide 25 0.0021 wt. Linoleic acid dimer salt(neutral) of N 3 dimethylaminopropyl) oleamide plus 0.0012 wt. N-(3-dimethyla'rninopropyl) oleamide 50 0.0024 wt. Linoleic acid dimersalt (neutral) of N-(3- dimethylaminopropyl) oleamide plus 0.0045 wt. N(3-dimethylaminopropyl) oleamide 50 0.0037 wt. Linoleic acid dimer salt(neutral) of N-(3- dimethylaminopropyl) oleamide plus 0.0067 wt. N-(3-dimethylaminopropyl) oleamide 0 0.0028 wt. Linoleic acid dimer saltneutral) oi N (3-dimethylaminopropyl) oleamide 10 0.0012 wt. Linoleicacid dimer salt (neutral) of N-(3- 7O dimethylaminopropyl) oleamide plus0.0022 wt. N-(3-dimethylaminopropyl) oleamide 125 0.0013 Wt. Linoleicacid dlmer salt (M neutral) of N- (3-dimethylaminopropyl) oleamide plus0.001 wt. linoleic acid dimer 125 6 EXAMPLE H A commercial premiumgasoline with a Reid vapor pressure of 11.0 lbs. and a mid-boiling pointof 228 F. was found to have a stall time of 0.75 minute when evaluatedin the throttle plate carburetor anti-stall test described in Example I.The same gasoline to which was added 0.0026 weight percent of thelinoleic acid dimer salt of N-(3-dimethylaminopropyl) tallamide gave astall time of 3.00 minutes, which represents excellent antiicingperformance.

EXAMPLE III A motor gasoline with a Reid vapor pressure of 7.1 lbs. anda mid-boiling point of 242 F. was found to cause an engine r.p.m. lossof 300 during 20 minutes operation when evaluated for anti-icing eifectin the emulsion tube carburetor test described in Example I. Theaddition of only 0.0014 weight percent of the linoleic acid dimer saltof N-(3-dimethylaminopropyl) oleamide caused the engine to operate onthe fuel for 20 minutes under the test conditions with no r.p.m. loss.

It is apparent from the preceding examples that the linoleic acid dimerand linoleic acid trimer salts of the fatty acid amino amides of thepresent invention are very effective in suppressing carburetor icing,whereas, as shown in Table II, the fatty acid amino amides and the dimerand trimer acids alone are markedly less effective.

EXAMPLE IV The linoleic acid-dimer and linoleic acid trimer salts of thefatty acid amide amines hereinabove described in this invention are alsoefrectve in improving the characteristics of gasoline in respect totheir ability to reduce or prevent the deposition of objectionable gumsand/ or carbonaceous materials in the carburetor.

The effect of the additives on the carburetor detergency properties ofthe gasoline was demonstrated using an Onan test engine equipped with aTillotsen carburetor modified by the use of removable inserts around thethrottle plate. Throughout the test, a portion of the exhaust gases of asecond single cylinder engine running at a constant speed of 1700 r.p.m.was introduced into the test carburetor. The test engine was cycled oneminute at open throttle under dynamometer load and then for two minutesat idle of 11001- r.p.m. for a period of two hours. At the conclusion ofthe test the inserts were removed and rated on a scale from 0 to 10where 10 represented bright and shiny and 0 represented very heavy blackdeposits.

The base gasoline described in Example I without the additive wasevaluated in the carburetor detergency test and found to give acarburetor inserts rating of 4.0. The same gasoline to which was added0.006 weight percent of the linoleic acid dimer salt ofN-(3-dimethylaminopropyl) tallamide gave a carburetor detergency testrating of 9.5, which is considered excellent detergency performance.

EXAMPLE V A commercial regular gasoline with a Reid vapor pressure of11.0 lbs. and a mid-boiling point of 210 F. gave a carburetor detergencyperformance rating of 6.4 when evaluated in the carburetor detergencytest described in Example IV. The same gasoline containing 0.005 Weightpercent of the linoleic acid dimer salt of N-(3-dimethylaminopropyl)tallamide was found to have a carburetor detergency performance ratingof 9.5.

It is to be understood that the preceding examples are representativeand that said examples may be varied within the scope of the totalspecification, as understood by one skilled in the art, to produceessentially the same results.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof it is to beunderstood that this wherein Ac represents a C to C acyl selected fromthe group consisting of aliphatic and cycloaliphatic acids and R and Rare individually selected from alkyl groups of 1 to 4 carbon atoms.

2. A gasoline composition comprising a gasoline and as an anti-stallingagent from about 0.001% to about 0.02% by weight based on the weight ofthe gasoline of a salt of (a) an acid selected from the group consistingof linoleic acid dimer and linoleic acid trimer and (b) adialkylaminopropyl carboxamide of the formula AC-NH-CH CH -CH NRR'wherein Ac represents a C to C acyl selected from the group consistingof aliphatic and cycloaliphatic acids and R and R are individuallyselected from the alkyl groups of 1 to 4 carbon atoms.

3. A gasoline composition comprising a gasoline and as an anti-stallingagent from about 0.001% to about 8 0.02% of the linoleic acid dimer saltof N-(B-dimethylaminopropyl) oleamide.

4. A gasoline composition comprising a gasoline and as an anti-stallingagent from about 0.001% to about 0.02% of the linoleic acid dimer saltof N-(3-dimethylaminopropyl) tallamide.

5. A gasoline composition comprising a gasoline and as an anti-stallingagent from about 0.001% to about 0.02% of the linoleic acid trimer saltof N-(3-dirnethylaminopropyl) tallamide.

6. A concentrated solution of an anti-stalling additive for gasolinecomprising a salt of (a) an acid selected from the group consisting oflinoleic acid dimer and linoleic acid trirner and (b) adialkylaminopropyl carboxamide of the formula Ac-NH-CH CH CH NRR',wherein Ac represents a C to C acyl selected from the group consistingof aliphatic and cycloaliphatic acids and R and R are individuallyselected from alkyl groups of 1 to 4 carbon atoms and methanol, saidsalt being in sufficient quantity to make a to by weight solution of thesalt.

References Cited UNITED STATES PATENTS 2,914,479 11/1959 Tom et al.44-66 X 2,922,707 1/ 1960 Lindstrom et al. 44-66 3,007,782 11/1961 Brownet al. 44-56 3,251,663 5/1966 Andress et al. 44-66 DANIEL E. WYMAN,Primary Examiner.

W. I. SHINE, Assistant Examiner.

6. A CONCENTRATED SOLUTION OF AN ANTI-STALLING ADDITIVE FOR GASOLINECOMPRISING A SALT OF (A) AN ACID SELECTED FROM THE GROUP CONSISTING OFLINOLEIC ACID DIMER AND LINOLEIC ACID TRIMER AND (B) ADIALKYLAMINOPROPYL CARBOXAMIDE OF THE FORMULA AC-NH-CH2CH2-CH2NRR'',WHEREIN AC REPRESENTS A C8 TO C18 ACYL SELECTED FROM THE GROUPCONSISTING OF ALIPHATIC AND CYCLOALIPHTIC ACIDS AND R AND R'' AREINDIVIDUALLY SELECTED FROM ALKYL GROUPS OF 1 TO 4 CARBON ATOMS ANDMETHANOL, SAID SALT BEING IN SUFFICIENT QUANTITY TO MAKE A 50 TO 80% BYWEIGHT SOLUTION OF THE SALT.